What Are The Causes Of Chemical Eye Injuries And How Can It Be Treated And Controlled

Most chemicals harm the eyes by direct contact with the external ocular tissues; these are amongst the most urgent ocular emergencies.

Concentratedsulphuric acid from exploding car batteries, household bleaches, detergents, disinfectants and lime are examples of chemicals that can cause burns to the eyes. However, it should not be forgotten that chemicals can also cause damage to the internal ocular structures, e.g. retina and optic nerve, through systemic absorption. 

Direct effect of chemicals

The main groups off chemicals that produce damage and that may be in the form of gas, vapor  liquid or solid are: organic solvents, surfactants, irritants and allergens, aerosols, alkali and acids.

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Indirect effects of chemicals

Chemicals come in various forms (solid, liquid, powder, dust, mist or vapor  and some can be toxic to the eye if they are accidentally ingested, absorbed or inhaled. Neurotoxic agents, such as organic solvents and heavy metals and their salts and alcohols, can cause optic neuritis or other ocular toxicities.

Treatment of chemical trauma

The ideal method of treatment is to neutralize the chemical. As this is often not possible and as time may be lost looking for the appropriate solution, immediate and prolonged irrigation of the eye with water or saline should be carried out. The faster the chemical is diluted, the better the prognosis. Water fountains, showers, etc. should be available in areas where chemicals are being used so that accidental spills or splashes of chemicals can be dowsed immediately with water.

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Recommended: Acid and Alkali Chemical Eye Injury

Irrigation should be continued for at least 20 minutes and the eye should not be padded, so that the tears continue to wash out any residual chemical. Any chemical particles that remain should also be removed. Various solutions are recommended for lime, mortar and plaster, including 11 percent disodium edetate, 10 percent ammonium tartrate, 10 percent glucose solution. For other alkali injuries, 2 percent boric acid or 2 percent acetic acid solutions are advised. For acid burns, 3.5 percent, sodium bicarbonate solution is advised.

In industries, an injured employee should be referred to the casualty department of the local hospital for further irrigation. Treatment then depends on the severity of the burn. In mild cases it may involve the instillation of topical antibiotics to prevent secondary infection and a mydriatic to dilate the pupil. The use of topical steroids is controversial. Whilst they have a beneficial effect in reducing the inflammatory reaction, they can retard the repair processes and hence lead to corneal melting and perforation.

In cases of alkali burns, citric acid has been shown to reduce the incidence of corneal ulceration in experiments by inhibiting polymorphs. Collagenase inhibiting, such as L-cysteine, have also been reported to have a beneficial effect in preventing ulcers in alkali burned corneas. The fitting of a scleral contact lens may help prevent adhesions of the bulbar and palpebral conjunctiva, i.e. symblepharon. A full thickness corneal graft may be necessary if the cornea is opaque but the prognosis is poor, especially if the cornea is vascularized.

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